Evolution of dust attenuation in star-forming galaxies with UV slope, stellar mass, and redshift out to $z\sim 5$

Abstract

Aims. We derive a dependence of the IRX on UV slope ${\hat{I}}^2$, stellar mass $M_{\ast }$, and redshift out to $z\simeq 5$, and establish consistent functional relations that can be used for correcting the UV/optical-selected galaxy samples for the effects of dust absorption. Methods. This work is based on a $K$-band selected sample of $\sim 10^5$ star-forming galaxies detected in the UDS and COSMOS fields. Quiescent sources and known starbursts are removed, and the IR luminosities are established through stacking in FIR {\it Herschel} and JCMT maps. UV slopes are found from SED fits and stacked IRX values are derived by taking the median of individual IRX measurements in bins of ${\hat{I}}^2$, $M_{\ast }$ and redshift. Results. While our best-fit IRX-${\hat{I}}^2$ relation is consistent with a Calzetti-like attenuation curve at ${\hat{I}}^2\gtrsim -1$, at bluer values the IRX seems to increase with redshift due to different mass-completeness limits imposed. When deriving the IRX-${\hat{I}}^2$ relation in stellar-mass bins, a systematic trend is found, where the effective slope of the attenuation law becomes progressively shallower with increasing mass. We incorporate this into the IRX-${\hat{I}}^2$ relation through the slope of the underlying reddening law, $d{A}_{1600}/d{\hat{I}}^2$, being a quadratic function of $\log (M_{\ast }/{\mathrm{M}}_{\odot })$. Expressing IRX as a function of the stellar mass we find a tight correlation, with IRX rising monotonically with mass but exhibiting a clear high-mass turnover at $z\lesssim 2-3$, consistent with suppressed cold-gas accretion and dust growth in massive systems.

13 pages, 8 figures and 5 tables, submitted to A&A